Endoscopic surgery has been gaining wide acceptance as an improved and cost effective technique for conducting certain surgical procedures. In endoscopic surgery, a trocar, which is a pointed piercing device, is sent into the body with a cannula placed around the trocar. After the trocar accomplishes piercing of the abdominal walls, it is removed and the cannula remains in the body. Through this cannula, endoscopic procedures are possible. Often multiple openings are produced in the body with a trocar so that an endoscopic instrument may be placed in one cannula, appropriate viewing mechanisms placed in another cannula and fiber optics for illuminating the surgical field placed in yet another cannula. Generally, these endoscopic procedures take place under insufflation. As more is learned about endoscopic procedures and more instruments developed, the type of procedures that may be performed endoscopically will increase. Presently, typical procedures are gall bladder removal, tissue repair and various sterilization procedures.
Broadly, the instruments used in surgery can be classified into two broad classes. One class is manipulation devices; that is, devices which will grasp tissue, position tissue, irrigate, apply suction, and the like. The second class may be termed active devices. Generally, these devices either cut or staple tissue and some devices may combine these actions. Examples of such devices are electrosurgery instruments, ultrasonic instruments, lasers, circular stapling instruments, linear stapling instruments, ligating and cutting instruments and the like.
While endoscopic surgical procedures have substantial benefits to the patient, they do present certain problems to the surgeon conducting the procedure. For example, because the active part of the instrument is further removed from the manipulative part of the instrument, any slight movement of that manipulative part is magnified when it reaches the active part. Hence, when placing and forming a staple in tissue, the hand of the surgeon must be a lot steadier during the endoscopic procedure than If that same procedure was done during standard open surgery. Another difficulty arises because the surgeon, conducting the procedure, cannot see the field in which he is operating in a direct manner but is watching that field on an appropriate video display and manipulating the instrument based on what he sees on that video display. Hence, in designing endoscopic surgical instruments, considerable effort is made to reduce the force required in order to operate the instrument and allow the surgeon to have greater control over the instrument. Also, from an engineering standpoint, considerable design engineering is required to permit function of the active portion of the instrument given the physical limits of force and stroke of the surgeon's hand.
Another problem, particular to endoscopic procedures, is that the surgeon can no longer feel tissue with his hands to determine thickness, consistency, texture, etc.
It should also be pointed out, that for medical reasons it is often desirable to make endoscopic instruments disposable. A major reason for this is that small, intricate, reusable instruments are difficult to sterilize and, if you can make the instrument disposable these sterilization problems are eliminated. However, making the instrument disposable will often increase the cost of the instrument and this cost must be balanced with the medical advantage. Another problem with endoscopic instruments is their access limitations; that is, the ability to manipulate the head of the instrument after it has been placed in the cannula is difficult and the scope of movement is limited.